From the coastal sage belt, into the yellow pine forest of the Pacific
slope, this species is common on land cleared by man or disturbed in the
course of construction, or on severely eroded slopes where the original
climax vegetation is partly or completely absent. Thus in the sage belt,
ground squirrels live along dirt roads through the brush, on the heavily
eroded banks often found in the foothills, on land grazed closely by
sheep, and in those parts of major washes such as San Antonio and
Cucamonga washes where scatterings of huge boulders offer prominent
vantage points. In San Antonio Canyon _Spermophilus_ was restricted to
the vicinity of roads and firebreaks, and an especially large colony of
at least forty individuals lived at a dump one mile southwest of Camp
Baldy at about 4500 feet elevation. Ground squirrels used burned stems
of large laurel sumac as observation posts. Because of a preference for
open areas offering unobstructed outlooks, ground squirrels originally
probably did not penetrate the main belt of heavy chaparral on the
Pacific slope of the range except in some of the large washes.
In the spring of 1951 and the preceding summer there was a marked
increase in the ground squirrel population near Padua Hills as a
result of sheep grazing on approximately one-half square mile of sage
land. Grasses and smaller shrubs were eaten down to the ground, and in
some places coastal sagebrush and _Haplopappus_ were killed by browsing
and trampling. The area formerly had a sparse growth of bushes with
intervening growths of tall grasses and one colony of perhaps 20 ground
squirrels; but after the sheep grazing the area was open brushland with
large clear spaces on which the herbage was trimmed to the ground, and
had at least four colonies of ground squirrels as large as the first.
Also there were other ground squirrels established in various parts of
the area. Probably the dry weather in the winter of 1950-51 with
consequent retardation of the vegetation aided the spread of the
squirrels in this area.
In the sage belt, most ground squirrels are dormant by December. In
1951, after a mild winter, squirrels were noted on January 25 near Padua
Hills. On February 8, 1951, males in breeding condition were collected,
and on March 16, a female taken near San Antonio Wash carried three
small embryos. In early March of 1951, ground squirrels were active at
4500 feet elevation in San Antonio Canyon.
_Specimen examined._--Los Angeles County: 1 mi. S and 2 mi. E
Big Pines, 8000 ft., 1.
=Spermophilus beecheyi fisheri= (Merriam)